1. Field of the Invention
This invention relates to an illumination device in which a light-emitting operation mode can be switched or changed by operating a mode-changing switch.
2. Related Art
There are known various illumination devices, and for example, an illumination lamp is mounted on an interior wall of a ceiling of a room of a vehicle such as an automobile. There is known one example of such vehicle room illumination lamps which comprises a housing having an incandescent bulb (hereinafter referred to merely as “bulb”) mounted therein, and a lens cover attached to this housing, and the bulb within the housing is turned on and off by operating a switch (see, for example, Unexamined Japanese Patent Publication 2002-79879)
Another example of such vehicle room illumination lamps is the type of illumination lamp (i.e., a so-called map lamp) including two illumination portions for respectively illuminating the driver's seat and the passenger's seat. In this vehicle room illumination lamp, bulbs of the two illumination portions are turned on respectively by operating switches of the two illumination portions.
In this vehicle room illumination lamp, a mode-changing switch is provided between the two illumination portions. By operating this mode-changing switch, the bulbs of the illumination portions are turned on and off in accordance with the opening and closing of a door of a vehicle. In recent years, such a vehicle room illumination lamp, thus having not only a light-emitting operation mode for merely turning on and off the bulbs of the two illumination portions but also a light-emitting operation mode (that is, a door opening/closing mode) for turning on and off the bulbs of the two illumination portions in accordance with the opening and closing of the vehicle door, has been used in many vehicles.
A three-conductor wire harness, having a battery wire, a grounding wire and a mode-changing courtesy wire, is used in a wiring circuit of the above second example of vehicle room illumination lamp. In each of the two illumination portions, a bulb terminal and a battery terminal are electrically connected to the battery wire and the grounding wire, respectively, and a courtesy terminal is connected to the courtesy wire. Further, in the mode-changing switch, two courtesy switch terminals are connected respectively to two electrically-separated end portions of that portion of the courtesy wire severed by stamping or the like. By switching this mode-changing switch, the separated wire portions of the courtesy wire can be electrically connected together and disconnected from each other.
In this circuit construction, the mode-changing switch for changing the light-emitting operation mode of the illumination portions by electrically connecting or disconnecting the separated wire portions of the courtesy wire need to be disposed closer to a DC power source for the wire harness. Therefore, the wire harness is connected to the mode-changing switch and the two illumination portions in this sequence from the power source.
In this wiring structure, the order of arrangement of the two illumination portions and the mode-changing switch on the housing (that is, one illumination portion, the mode-changing switch and the other illumination portion are arranged in this order on the housing) is different from the order of connection of the wire harness to the two illumination portions and the mode-changing switch. Therefore, the wire harness must be installed over a long distance in accordance with the arrangement of the illumination portions and mode-changing switch.
As a result, the installation of the wire harness as well as a holding structure of the housing becomes complicated, and therefore the assembling operation is cumbersome, and besides the wire harness has an increased length, so that the cost increases.
Furthermore, there is the type of vehicle equipped not only with such a vehicle room illumination lamp (that is, a so-called map lamp) but also with a vehicle room illumination lamp (that is, a so-called personal lamp) for illuminating a rear seat or others of the vehicle. In such an illumination lamp, a wiring circuit of the map lamp and a wiring circuit of the personal lamp are separate from each other, and therefore it is necessary to provide separate door opening/closing-mode courtesy wires, and therefore it is necessary to provide wire harnesses of different circuits. Similarly, two mode-changing switches need to be provided, so that the structure becomes complicated.
Thus, in the above vehicle room illumination lamp, the number and length of the wire harnesses increase, and also the number of the switches increases, and therefore the installation of the wire harnesses and the holding structure have become complicated, and the assembling operation has become cumbersome, and besides the cost has increased.